Earth Science: Lithosphere, Faults, and Seismic Activity

A set of flashcards covering key vocabulary terms and concepts related to geology, tectonic activity, seismic waves, and earthquake engineering.

Lithosphere

The outermost, rigid layer of the Earth, consisting of the crust and the rigid upper part of the mantle.

Asthenosphere

A plastic layer of the mantle on which pieces of the lithosphere move and flows very slowly.

Mesosphere

The strong lower part of the mantle that extends from the bottom of the asthenosphere to the Earth's core.

Outer Core

The liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core.

Inner Core

The solid dense center of the Earth, extending from the bottom of the outer core to the center of the Earth.

Crust

The outermost layer of the Earth made of oxygen, silicon, and aluminum.

Mantle

The layer of the Earth beneath the crust made of magnesium, aluminum, and silicon.

Core

The innermost layer of the Earth composed mainly of iron and nickel.

Plate Tectonics

Large movable plates under the Earth's surface.

Convergent Boundary

The boundary formed by the collision of two lithospheric plates.

Divergent Boundary

The boundary between two tectonic plates that are moving away from each other.

Transform Boundary

The boundary between tectonic plates that are sliding past each other horizontally.

Normal Fault

A geological fault where rocks move apart, with the hanging wall moving downward relative to the footwall.

Reverse Fault

A geological fault where rock layers are pushed together and one side moves upward relative to the other.

Strike-Slip Fault

A fault where two blocks of rock slide past each other horizontally.

Focus of an Earthquake

The point within the Earth where an earthquake originates.

Epicenter

The point directly above the focus of an earthquake on the Earth's surface.

Seismic Waves

Waves of energy that travel through the Earth, including body waves and surface waves.

Primary Waves (P Waves)

The fastest seismic waves that can travel through solids, liquids, and gas and compress in the direction of wave movement.

Shear Waves (S Waves)

Seismic waves that shear rock side to side and cannot travel through liquids.

Surface Waves

Seismic waves that move along the Earth’s surface, affecting the upper few kilometers of the crust.

Mercalli Scale

A measure of earthquake intensity that assesses damage based on observations.

Richter Scale

A scale that measures the strength and energy released by an earthquake.

Continental Drift

The theory that tectonic plates move, causing continents to separate, collide, and slide.

Sea-Floor Spreading

The process by which new oceanic lithosphere forms as magma rises toward the surface.

Magnetic Reversal

The phenomenon when Earth's magnetic poles change places and the polarity of the magnetic field shifts.

Tectonic Activity

Movement of tectonic plates associated with earthquakes and geological changes.

Induced Earthquake Activity

Earthquakes caused by human activities such as mining or reservoir-induced seismicity.

Compression

A stress that pushes rocks together, often resulting in reverse faults.

Tension

A stress that pulls rocks apart, typically leading to normal faults.

Shear Stress

A force that causes pieces of rock to slide past each other.

Raleigh Wave (R Wave)

A type of surface wave that moves up and down and is the slowest and most destructive.

EPICENTER TRIANGULATION

Using data from multiple seismograph stations to determine the location of an earthquake epicenter.

Time Lag

The difference in arrival times between P waves and S waves used to calculate distance to an epicenter.

Amplitude of a Wave

The distance from the crest to the trough of a wave.

Building Base Isolators

Devices designed to absorb seismic energy to minimize building movement during an earthquake.

Pendulums in Construction

Heavy weights that can shift to counteract the movement of a building during seismic activity.

Arch Structures

Shapes used in construction that help distribute weight and increase stability.

Triangle Shapes in Construction

Shapes that provide strength through geometry, often used in trusses for stability.

Earthquake Monitoring Equipment

Instruments such as seismographs used to detect and record seismic waves.

Tectonic Plate Collision

When two tectonic plates collide, resulting in geological formations like mountains and trenches.

Volcanic Activity

Processes related to the eruption of volcanoes that can trigger earthquakes.

Seismic Wave Propagation

The way seismic waves travel through different materials in the Earth.

Earthquake Damage Assessment

Evaluating the extent of destruction caused by an earthquake based on location and building integrity.

Locating Earthquake Epicenter

Determining the distance of an epicenter using graphs and mathematical formulas.

Earthquake Aftershocks

Smaller seismic events that follow a larger earthquake, often occurring in the same region.

Seismic Wave Classification

Categorizing seismic waves as either body waves (P and S) or surface waves based on their properties.

Fault Diagram Elements

Key components such as footwall and hanging wall used in visualizing fault structures.

Ground Movement Direction

The motion caused by seismic waves, which can be vertical or horizontal.

Geological Fault Types

Different categories of faults such as normal, reverse, and strike-slip based on their movement.

Natural Frequency

The frequency at which a system naturally vibrates; can amplify seismic waves.

Cross Bracing

Structural support used in buildings to enhance stability and resist lateral forces.

Seismic Energy Absorption Techniques

Methods and technologies used during construction to mitigate earthquake damages.

Seismic Severity Assessment

Evaluation of the potential damage an earthquake could cause based on intensity and location.

What are seismic waves?

Waves of energy that travel through the Earth, generated by earthquakes or other geological activity.

What are body waves?

A category of seismic waves that travel through the Earth's interior, including Primary Waves (P waves) and Shear Waves (S waves).

What are surface waves?

Seismic waves that travel along the Earth's surface and are typically more damaging than body waves.

What is a Primary Wave (P Wave)?

The fastest seismic wave that travels through solids, liquids, and gases, compressing in the direction of wave movement.

What is a Shear Wave (S Wave)?

A type of seismic wave that moves side to side and cannot travel through liquids.

What is an Amplitude of a Wave?

The distance from the crest to the trough of a wave, indicating its energy.

What are Raleigh Waves (R Waves)?

A type of surface wave that rolls across the ground and is the slowest and most destructive type of seismic wave.

What is wave propagation?

The way seismic waves travel through different materials in the Earth.

What is wave frequency?

The number of wave cycles that pass a point in a given period of time; can affect the energy of seismic waves.

What is seismic wave classification?

The categorization of seismic waves as either body waves (P and S) or surface waves based on their characteristics